The survey of pathologic lesions of trachea in co-administration of H120 and 4/91 IB vaccines in broiler chickens

Infectious bronchitis (IB) disease is one of main infectious disease in poultry production. IB virus posses several serotype that the immunity against each serotype is specific. The protection against any serotype is expected by vaccination against the same serotype. In Iran, the Massachusetts and 4/91 serotypes are common and different commercial IB vaccines were utilized against these serotypes. By considering to this fact that there is no interference between different IB virus serotypes, this seems that administration of different IB vaccines simultaneously or by short interval time can be effective for increasing of protection level. Therefore, in this study the vaccinal reaction was studied following of administration of two distinct IB vaccines by pathological examination. For this, in commercial farms the H120 and 4/91 vaccines administrated distinctly and simultaneously. In this study the vaccination programs were examined and compared with pathological examination of trachea. The result represents that co-administration of H120 and 4/91 can induce higher pathologic lesions on trachea. It concluded that in IB vaccination, it is better to administrate different vaccines with interval time and do not vaccination simultaneously.